Composite alloy



Nov. 17, 1953 T. E. LEONTIS ET AL 2,659,135

COMPOSITE ALLOY Filed Aug. 16, 1950 IN VEN TORS. T homas E. Leon/i5 BY Rober/ 5. BuS/ A TTORNE YS Patented Nov. 17, 1953 UNITED ATES COMPOSITE ALLOY ware Application August 16, 1950, Serial No. 179,779

8 Claims. 1

The invention relates to a magnesium-base alloy article. It more particularly concerns a composite magnesium base alloy containing manganese.

The term magnesium-base alloy used herein means a magnesium alloy containing at least 80 per cent of magnesium by weight.

One of the well-known magnesium-base alloys containing manganese is the binary magnesiummanganese alloy which usually contains about 1.5 per cent of manganese, the balance being magnesium. Its outstanding characteristics are lightness of weight, superior resistance to corrosion, and lack of stress corrosion sensitivity. In spite of these desirable characteristics, the alloy is not as generally used as some of the other commercially available magnesium-base alloys because it possesses somewhat lower strength.

The principal object of the present invention is to provide an improved metal product comprising the conventional binary magnesium-base magnesium manganese alloy exhibiting high strength and method of making the same.

The invention is predicated upon the discovery that by die-expressing a comminuted form of the magnesium-base magnesium-manganese alloy in admixture with at least two of the magnesiumsoluble metallic elements of the group: cadmium, lead, manganese, tin, silver, and zinc, a composite alloy comprising the magnesium-base magnesium-manganese alloy is obtained having improved strength. The composite alloy thus obtained may be subjected to any of the fabrication operations conventionally used with ordinary magnesium-base alloys, such as rolling, forging, drawing, welding, heat treatment, etc. The invention then consists of the composite magnesium-base alloy product and method of making the same herein fully described and particularly pointed out in the claims, the following description setting forth several modes of practicing the invention.

In carrying out the invention, the magnesiumbase magnesium-manganese alloy used may contain manganese in various proportions, e. g. from about 0.5 to 2.5 per cent, although preferable proportions are about 1 to 1.8 per cent, the balance being commercial magnesium. The alloy is reduced to particulate form in any convenient manner, such as by grinding or atomizing. The atomized form is preferred and may be produced by forming a melt of the alloy and atomizing it by impinging a jet of a cool gas, e. g. natural gas, against a thin falling stream of the molten alloy. The atomized alloy consists of a mixture of various sized fine spherical rapidly solidified particles, the particles having a very fine grain structure. It is desirable to screen out particles coarser than those passing about a 10 to 20 mesh s1eve.

The magnesium-soluble metals with which the particulated magnesium-manganese alloy are to be mixed may be reduced to particulate form in any convenient manner. Their particle size preferably is made finer than that of the magnesium-base alloy.

Before extrusion, the particulated metals are mixed together in any convenient manner to form a uniform mixture of the metal particles composing the extrusion charge. The amounts of the particulated magnesium-soluble metal in the extrusion charge may be from about 1 to 9 per cent, a preferred proportion being about 2 per cent, the balance of the extrusion charge being the aforesaid particulated magnesium-base magnesium manganese alloy. The relative amounts of the two particulated magnesiumsoluble metals in the extrusion charge may be varied from a minimum of about 10 per cent to a maximum of about per cent of one soluble metal, the balance being the other. A preferred ratio of the amount of one of the two magnesium-soluble metals with respect to the other in the extrusion charge is about 1:1.

The mixture of particulated metals is charged into the heated container of a ram extruder, having a suitable size contain-er and die-opening and. subjected to extrusion pressure to cause the mixture of particulated metals to be heated and extruded through the die opening.

As to the extrusion conditions, the temperature of the particulated metal mixture in the container may be about the same as that conventionally employed for extruding solid ingots of the known manganese-containing magnesiumbase alloys, e. g. 600 to 850 F. The ratio of the cross-sectional area of the extrusion container to that of the die opening has a material efiect on the mechanical properties of the composite extrusion product obtained. A desirable ratio is at least about 30 to 1, although ratios as high as to 1 or more may be used. The speed of extrusion may be varied over a wide range and depends to some extent upon the size and shape of the die opening, in any case the speed is to be held down to that at which the extrusion produced is free from hot shortness. A safe extrusion speed may be ascertained by visual examination of the product as it extrudes, the hot shortness being .evident as cracks in the extruded product and sharply reduced strength.

The invention may be further illustrated and 3 explained in connection with the accompanying drawing in which:

Fig. 1 shows a schematic sectional elevation of an extrusion apparatus suitable for use in pracextrusion, the metals originally in the charge as individual metal particles become Welded together without voids and do not lose their original distinctive composition except at the united surfaces of the particles which become extended and ticing the invention;

Fig. 2 is a similar'view to Fig. 1 showing a modllengthened during extrusion. At these surfaces, ficationof the apparatus; and duringv extrusion or heat treatment, some dif- Fig. 3 is a similar view to Fig. 1 showing anfusion of metal takes place between the manother modification of the apparatus. ganese-containing particles and the magnesium- As shown, the apparatus comprises, in its three soluble metal particles. forms, an extrusion container l adapted to con- The following examples set forth in the table fine a charge 2 of the mixture of metal particles below are illustrative of the invention:

Table Composition 1])! Egtrulon Charge of Particu ate .1 agnesiun'l- I r 4 X r Base Alloy Mixed. with Pap Mechanical P.0pelide1gt1l:& l. of h truslous ticulated Ma nesium-Soluble Metals A and B 1 l vN Reduction Extluslon l l lfNd in Area Size Inch 0 s A 1 11.1. H. '1". wt Pep M Soluble Metal A X ge A cent AHOY A Percent B Percent TYS Ts TYS 'lS TYs Ts TYS Ts 31:1 0.090 32 40 a2 44 :11 e0 0 31:1 0. 000 40 47 42 34 42 33 2 0 31:1 0. 000 44 47 44 40 30 41 :13 42 .0 31 :1 0. 090 41 47 3 4s 32 41 41 ,0 31: 1 0. 000 42 4s 4s 33 42 :44 41 .0 :11 :1 0. 0110 .19 47 41 2s :10 20 40 5 :11 :1 0. 000 40 40 41 4s 31 42 .20 40 0 31:1 0. 000 47 41 40 32 41 :11 41 5 31:1 0. 000 40 4 41 49 32 42 24 42 v .0 s1=1 0.020 44 1 43 40 :14 41 34 41 2a 0 31:1 0. 090 4g 4 42 2 40 r. 93.0 .4:1 0.086 3 4 4a a. 42 98. 0 1: 1 0v 44 45 47 37 41 11s 41 Example 1 9s. 0 54:1 0. one 40 4a 42 s0 59 as 4 Example 14. 9s. 0 34:1 0. 020 41 42 44 45 3s 41 3s 00 Example 15... 93.0 3 :1 0. 030 as 40 45 a 40 3s 41 Example 10. 0s. 0 34:1 0. 080 a 44 :10 40 41 2:: 42 Example 1/. 0 34: 1 0. 02.0 2 42 37 45 e4 42 34 41 Example 18... 9s. 0 34:1 0. use a 44 39 40 24 41 11 Example 10... 911.0 34:1 0. 0st 45 as 40 43 37 41 Example 20. 0s. 0 34:1 0. 000 42 3 42 45 :11 40 241 :19 Example 21. 0 34:1 0. 086 :49 42 42 44 33 39 37 19 Example 22... 01.0 31:1 0. 090 3 44 57 45 37 43 30 43 Example 23 e1. 0 31:1 0. 000 37 43 40 44 3 40 41 1 1.6% M11, balance Mg. 2 Wire.

3 ASX=as extruded.

Aged=heat treated for 16 hours at 350 F. E. T.=E'.eat treated for 1 hour at 750 F.

H. T. AFB-eat treated for 1 hour at 750 F. followed by. heat treatmentfor 16 hours at 350? F. TYS=Ter1sile yield strength, defined as the stress at which the stress strain curve deviates 0.2% from the modulus 11.110.

TS =Tellsile strength.

to be compacted and extruded. The container is provided with a heating element In Fig. 1, one end of the container i is closed by the die plate ii in which is provided the die opening 5. In this form of the apparatus, the charge 2 is caused to be compacted in the container and extruded through the die opening 5 by application of pressure by means of the dummy block 6 which is forced into the here 1' of the container by the ram 3 to form the extrusion 9.

In the form of the apparatus shown in Fig. 2, the container i is closed at one end by the plate E5. The other end of the container receives the die blocl: I! carried by the hollow ram l2 which forces the die block. into the container causing the charge 2 to be compacted and to extrude through die opening [3 toform the extrusion M which extends into bore E5 of the hollow ram l2.

In the modification of Fig. 3, the container is closed at one end with a plate H5. The charge 2 is extruded as a tubular extrusion I? through the annulus i3 around the die block l9 which is forced into the container by the ram 28.

The forms of the apparatus shown are conventional.

By putting a charge of the mixture of the particulated metals involved under pressure while at heat, as with the apparatus shown the metal particles are not subjected to further mixing before In making the composite alloys shown in the foregoing table, the manganese-containing magnesium-manganese binary alloy used was in atomized form, the particles of which were of various sizes substantially all passing through 20 mesh sieve while being retained on a 200 mesh sieve. The particles of the particulated magnesium-soluble metal were of generally finer size than those of the magnesium alloy used. The particulated metals were mixed together in the proportions shown and the mixture charged into the container or" a ram extruder of the type illustrated in Fig. 1. For the blank, the man ganese=containing magnesium-base alloy, in the same particulated form as used in the mixture was extruded alone under comparable extrusion conditions. The rate of extrusion was about 1 to 2 feet per minute, and the temperature about 700 F.

We olaimz 1. The method of making. a solid composite high strength metal comprising magnesium alloyed with manganese which comprises forming a mixture of a particulated binary magnesiummanganese alloy containing from 0.5 to 2.5 per cent of manganese, the balance being magnesium, and at least two particulate magnesiumsoluble metals selected from the group consisting of cadmium, lead, manganese, tin, silver, and

zinc, said magnesium-soluble metal forming from 1 to 9 per cent of the weight of the mixture the balance of the mixture being said binary alloy, and die-expressing the mixture at a temperature from 600 to 850 F.

2. The method according to claim 1 in which two magnesium-soluble metals are used and the amount of one of the magnesium-soluble metal is from 10 to 90 per cent of the total amount of magnesium-soluble metal in the mixture.

3. The method according to claim 2 in which the two magnesium-soluble metals are zinc and tin.

4. The method according to claim 2 in which the two magnesium-soluble metals are zinc and manganese.

5. The method according to claim 2 in which the two magnesium-soluble metals are zinc and cadmium.

6. The method according to claim 2 in which the two magnesium-soluble metals are silver and manganese.

7. The method according to claim 2 in which the two magnesium-soluble metals are silver and tin.

8. A composite metal body comprising a particulate binary magnesium-base magnesiummanganese alloy containing from 0.5 to 2.5 per cent of manganese the balance of the alloy being magnesium and at least two particulate metals selected from the group consisting of cadmium, lead, manganese, tin, silver, and zinc, in amount between 1 and 9 per cent of the weight 6 of the said body the balance of the said body being the said binary alloy, the particles of each metal being elongated, oriented in the same direction and welded together into an integral solid.

THOMAS E. LEONTIS.

ROBERT S. BUSK.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES "Treatise on Powder Metallurgy by Goetzel, vol. 2, pp. 500, 740, 741, published in 1950. (Taken from Arch. Metallkunde, 1 No. 7/8 363, 1947.)

Symposium on Powder Metallurgy, Buffalo Spring Meeting, March 3, 1943, published by American Society for Testing Materials, Philadelphia, Pa., pages 42 and 43. 

8. A COMPOSITE METAL BODY COMPRISING A PARTICULATE BINARY MAGNESIUM-BASE MAGNESIUMMANGANESE ALLOY CONTAINING FROM 0.5 TO 2.5 PER CENT OF MANGANESE THE BALANCE OF THE ALLOY BEING MAGNESIUM AND AT LEAST TWO PARTICULATE METALS SELECTED FROM THE GROUP CONSISTING OF CADMINUM, LEAD, MANGANESE, THIN, SILVER, AND ZINC, IN AMOUNT BETWEEN 1 AND 9 PER CENT OF THE WEIGHT OF THE SAID BODY THE BALANCE OF THE SAID BODY BEING THE SAID BINARY ALLOY, THE PARTICLES OF EACH METAL BEING ELONGATED ORIENTED IN THE SAME DIREACTION AND WELDED TOGETHER INTO AN INTEGRAL SOLID. 